1. Field of the Invention
The present invention relates to a sequential rotated feeding circuit, and in particular relates to a sequential rotated feeding circuit with decreased dimensions.
2. Description of the Related Art
Sequential rotated feeding circuits are utilized for feeding signals to an antenna array. There are three types of conventional sequential rotated feeding circuits: (a) Parallel type, (b) Series type, and (c) Hybrid ring with parallel type. A conventional sequential rotated feeding circuit is relatively large. For example, a parallel type sequential rotated feeding circuit has a circuit area about
                    3        ⁢        λ            4        ×                  3        ⁢        λ            4        ,wherein λ is a wavelength of a wireless signal transmitted by the antenna array. A series type sequential rotated feeding circuit has a circuit area about
      λ    4    ×                    3        ⁢        λ            4        .  A hybrid ring with parallel type sequential rotated feeding circuit has a circuit area about.
  λ  ×                    3        ⁢        λ            4        .  The large dimensions of the conventional sequential rotated feeding circuit causes increased distances between antenna units of the antenna array, which generates a side lobe, and deteriorates signal transmission effect.
Additionally, for conventional sequential rotated feeding circuit, different line width designs are utilized (more than four line width designs) to satisfy resistance matching requirements. Thus, the design of conventional sequential rotated feeding circuit is complex, with large circuit area.